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NRC proposes changes to its rules on nuclear materials
In response to Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” the NRC is proposing sweeping changes to its rules governing the use of nuclear materials that are widely used in industry, medicine, and research. The changes would amend NRC regulations for the licensing of nuclear byproduct material, some source material, and some special nuclear material.
As published in the May 18 Federal Register, the NRC is seeking public comment on this proposed rule and draft interim guidance until July 2.
N. V. Kornilov
Nuclear Science and Engineering | Volume 186 | Number 2 | May 2017 | Pages 190-198
Technical Paper | doi.org/10.1080/00295639.2016.1273625
Articles are hosted by Taylor and Francis Online.
The traditional assumption of prompt fission neutron spectra (PFNS) integrated over emission angle applies for any calculation of the neutron interaction inside fissile material. Only these evaluated data are included in any neutron data library. But this is not correct. Prompt fission neutrons have very strong angular energy distribution relative to fission fragment (FF) direction. The FFs have anisotropy relative to direction of incident neutrons. What is the influence of this assumption or simplification? Results of Monte Carlo simulation are submitted in this paper. The incorporation of “real” angular energy distribution changes the yield of 238U fission, and this difference may be compensated by changing the average energy of PFNS in the traditional approach. This effect is connected with correlations between different characteristics of interacted neutrons inside the environment. An additional type of correlation between multiplicity and energy of fission neutrons, named ν-E correlation, is also discussed.
